Temperature responsive force transmitting device



Dec. 12, 1967 s. VERNET 3,357,252

TEMPERATURE RESPONSIVE FORCE TRANSMITTING DEVICE Filed May 4, 1966 2Sheets-Sheet 1 INVENTOR.

'sery l'us Verne) A rom 5Y5 Dec. 12, 1967 s. VERNET 3,357,252

TEMPERATURE RESPONSIVE FORCE TRANSMITTING DEVICE Filed May 4, 1966 2Sheets-Sheet'Z United States Patent 3,357,252 TEMPERATURE RESPONSIVEFORCE TRANSMITTING DEVICE Sergius Vernet, Yellow Springs, Ohio, assignorto Antioch College, Yellow Springs, Ohio, a corporation of Ohio FiledMay 4, 1966, Ser. No. 554,258 13 Claims. (Cl. 73368.3)

This invention relates to temperature sensitive motion transmittingdevices or thermal sensitive elements and is more particularly directedto a device of this character having a greatly improved means forproviding a fluid tight seal for the thermal expansion material andhaving novel construction features which permit the development of anextremely small diameter thermal element.

The present application is a continuation-in-part of my co-pendingUnited States patent application Ser. No. 215,- 720 and now abandoned.Several responsive elements are now widely used as a means forenergizing a wide variety of components as a function of changes inambient temperature. Generally, they comprise a casing having a thermalexpansion material contained therein, a closure cap or guide providing abore, a diaphragm or seal interposed between the expansion material andthe cap, and a power member or piston guided for movement within thebore and bottomed on the seal. When the temperature of the expansionmaterial is raised to a predetermined point, the material expands andthis expansion is transmitted through the seal to the power member whichis thereby caused to move extensively from the bore.

Heretofore several responsive elements have generally been formed in twoparts wherein outwardly extending flanges of an upper and lower casingare used to sandwich the peripheral lip of the boot therebetween tomaintain the boot in its proper position within the casing. A columnmember is then fitted over the out turned flanges of the casing elementsand is then peened down or pressed down snugly on top of the flange ofthe upper casing element to positively secure the casing elementstogether. Due to the necessity for the outwardly extending flanges inorder to secure the peripheral lip of the boot within the casing, thethermal responsive element has been substantially larger in diameterthan has been found to be desirable. Thermal responsive elements havingsuch outwardly extending flanges may be referred to as having aso-called horizontal seal. Many uses of thermal responsive elements,however, are required to have a minimum diameter which requirement is indirect conflict with the necessity for having outwardly extendingflanges on the upper and lower casing elements. Accordingly it would behighly desirable to provide a means for eliminating the outwardlyextending flanges and consequently minimizing the size of the thermalresponsive element.

Also, the life of thermal responsive elements heretofore employed in theart has not been entirely satisfactory, particularly in those instancesin which the elements are subjected to the forces of highly pressurizedwater. The reasons for the undesirably short life of these elements islargely twofold. First, ineflicient seals permit the expansion materialto seep out of the casing with continued element use. Second, and muchmore importantly, pressurized water acting on the exterior of theelement at the cap and around the guide, forces its way past the cap andseal and into the chamber containing the thermal expansion material. Theentering of water into this chamber may considerably alter the operatingcharacteristics of the element and may, in time, prevent the elementfrom operating at all.

I have found that seal loosening is generally caused by movement of thepower member relative to the casing of the thermal sensitive element.When the power member moves extensively with respect to the casing, theseal or diaphragm is forced tightly against the piston guide. However,when the power member moves retractibly with respect to the casing, theinner end of the power member acts against the diaphragm or seal to pullthe seal away from its normal seated position against the power memberguide, and water seeps into the casing through the cracks formed betweenthe metal-to-metal contacting members of the unit.

I have devised a means for preventing loosening of the seal as aconsequence of reciprocal movement of the power member. Generally, myinvention resides in the provision of a guide having a depending bossextending into the casing which boss has a groove formed in the sidewall thereof for receiving a complementary lip formed on the diaphragmor. seal. The diaphragm or seal lip is maintained in compression betweenthe side wall of the boss and the side wall of the casing, so a portionof the seal is always urged into the groove in a depending boss.Loosening of the seal as a result of extension and retraction of thepower member is effectively obviated in this manner.

I have also discovered that seal leakage may be caused I by contractionor expansion of the seal or diaphragm as a result of exposure to veryhot or cold temperatures. I have devised a means for maintaining theseal in good sealing relation with the casing, the piston guide, and thepiston itself which effectively obviates the problems heretoforeencountered under such conditions. In addition, I have found that byforming the piston guide of sintered material or a liquid permeablematerial, liquid trapped between the piston and the boot or water whichhas seeped into the casing can emerge through the guide. It is thereforea principal object of my invention to provide an improved temperatureresponsive force transmitting device.

It is also an object of my invention to provide a thermal sensitiveforce transmitting device having a greatly reduced diameter.

It is another object of my invention to provide thermal sensitiveelement which is so designed as to prevent seal leakage. 7

Another object of my invention resides in the provision of a thermalsensitive element having means for preventing movement of the sealingportion of a boot or diaphragm as a consequence of reciprocal movementof the power member.

Another object of my invention is directed to the formation of a powermember guide of a liquid permeable material to obviate trapping ofliquid in the boot by allowing liquid to pass freely through thepermeable material.

Also, one of the primary reasons for designing the thermal sensitiveelement in the manner set forth above is to reduce the overall diameterof the unit. The usual type of thermostat with the flange for sealingthe guide to the cup adds considerably to the diameter of the unit andthis new design obviates this undesirable characteristic.

These and other objects, features and advantages of this invention willbe more clearly understood from the following description and theassociated drawing wherein reference numerals are utilized indesignating an illustrative embodiment and wherein:

FIGURES l, 2 and 3 are vertical sectional views through a temperatureresponsive force transmitting device in the process of assembly;

FIGURE 4 is a vertical sectional view through a completed temperatureresponsive force transmitting device constructed in accordance with myinvention;

FIGURE 5 is a vertical sectional view through another embodiment of myinvention;

FIGURE 6 is a vertical sectional view through another improved form ofthermal sensitive units;

FIGURE 7 is a vertical sectional view through a cup type thermalsensitive power unit; and

FIGURE 8 is a vertical sectional view through that form of my inventionwhich employs a guide formed of a water permeable material.

Referring initially to FIGURE 4, a cylindrical casing 10 is formed of ametal or suitable heat conductive material and has an inturned annularflange 11 formed at one end thereof and defining an aperture 12. A metaldisk 13 is seated upon the flange 11 and serves, in turn, as a seat fora resilient disk seal 14. This method of sealing one end of atemperature responsive: force transmitting device is well understood bythose skilled in this art and does not constitute part of my invention.In fact, the casing 10 could be formed with a closed end at the base sothat the disk and seal 13 and 14 would not be necessary.

An expansion material 15 is contained within the easing 10 and alsoneeds no detailed explanation to those skilled in the art. It generallycomprises a wax substance which may be impregnated with a metallicpowder and which will expand when its temperature has been raised to apredetermined point.

My invention is more specifically directed to the means for sealing theupper end of the causing through which the power member or piston 16moves. Also, by sealing the boot within the casing according to myinvention, the entire thermal power unit can be formed of a greatlyreduced diameter and consequently can be utilized for heretoforeunintended applications.

In FIGURE 4, a guide 17 is fitted within the upper end of the casing andis maintained in its proper position by an annular inturned flange 18which is rolled or crimped over the outer end face 19 of the guide 17.The guide 17 has a side wall 20 which tapers inwardly from the end face19 thereof. A boss 21 depends from the inner end face 22 of the enlargeddiameter portion of the guide 17, and a bore 23 extends centrallythrough the guide 17 and serves as a guide for the power member 16. Aresilient boot 24 is formed of rubber or like materials and extendsacross the interior of the casing 10 and into the lower portion thereof.Note should be made of the fact that the term seal will hereafter oftenbe used to encompass not only such seals as the boot 24 but also toencompass diaphragms or combination diaphragm plugs which are fainiliarto those skilled in the art. The thermal sensitive element illustratedin FIGURE 4 does employ a boot, but this is only one form of thermalsensitive elements, and many forms are well known to those skilled inthe art which could employ my invention in equally as satisfactory afashion.

The boot 24 has an annular lip 25 formed at the upper end thereof whichis fitted between the inner side wall 26 of the casing 10 and the sidewall 27 of the depend? ing boss 21. A rounded groove 23 is formedcircumferentially about the upper end of the boss 21 and receives anannular head 29 formed at the upper end of the lip 25. A thin walledsection of the boot 24 extends upwardly into. the tapered crevice formedbetween the side wall 20 and the inner side wall 26 of the casing 10, sothat a fluid tight seal is formed between the casing 10 and the guide 17. A bore 30 is formed within the boot 24 and re? ceives the lowermostend of the power member or piston 16. The type of element illustrated inFIGURE 4 is a squeeze element and derives its name from the manner inwhich the piston 16 is forced to move extensibly from the guide 17. Whenthe expansion material 15 has its temperature raised to a predeterminedcritical point, the material will expand and expansion of this materialwill act to compress the side walls of the boot around the lower end ofthe piston. The lower end of the piston 16 tapers, as at 31, to a point,so that the squeeze of the side walls by the expansion material 15 tendsto force the piston 16 upwardly within the bore 23. This squeeze effectacts to extensibly move the power member 16 from the guide 17 Variousmeans are provided for returning the piston- 16 to the positionillustrated in FIGURE 4 upon cooling of the material 15, and such meansmay, of course, comprise a simple spring acting against the outer end ofthe piston or against a collar mounted on the piston. Such means arewell known in the art and are not here illustrated or further described.Regardless, means are pro vided for returning the piston 16 to theposition illustrated in FIGURE 4. Such retractible movement of thepiston 16 normally acts to pull the boot 24 downwardly within the casing10 and such continued pulling of the boot acts over a period of time tocause seal failure and to permit the seepage of water into the interiorof the casing where the expansion material 15 is continued.

By forming the boot 24 with a bead 29 at the upper end of the lip 25,such pull down of the boot 24 is effectively resisted.

It is important to understand that the lip 25 of the boot 24 ismaintained in position between the casing wall and the side wall of theboss 21 in a compressed state. Also, the thin walled portion 25a istightly wedged be tween the side wall 20 and the inner wall of thecasing. Such compression and wedging is attained by the manner in whichthe unit is assembled which is clearly illustrated in FIGURES l, 2 and3. Referring to FIGURE 1, it will be observed that the guide 17, piston16, and boot 24 have been assembled as a single unit. The boot 24 has athin walled outwardly extending integral flange 32 extending from theupper end of the boot adjacent the bead 29. In an unstressed condition,the outer diameter of the boot 24 at and adjacent to the lip 25 issomewhat greater than the inner diameter of the casing 10. As a result,when the boot, guide, and piston are forced into the casing, the lip 25is put under compression to provide a positive seal between the guideand the inner wall of the casing. Also, since an outwardly extendingflange is not required in order to secure the resilient boot within thecasing, a thin cylindrical casing, such as the casing 10 may be employedfor containing the thermal element. In additron, it may be noted thatthe inner surface of the cylindrical casing, such as the casing 10 maybe employed for containing the thermal element. In addition, it may benoted that the inner surface of the cylindrical casing 10 may be asubstantially smooth wall such that the cost of forming the casing canbe considerably reduced over casings heretofore used which have beenspecially constructed for the purpose of supporting the resilient boottherein. a

As shown in FIGURE 2, the flange 32 will be bent upwardly as the guideand boot are moved into the easmg. The thin walled flange 32 will becomewedged between the tapered side wall 20 of the guide 17 and the innerwall 26 of the casing 10, and the outer edge thereof will finally beclipped otf as the uppermost end of the guide 17 is forced into positionwithin the casing 10. As a result, the thin walled section of the 'boot24 will become tightly wedged between the guide and the casing, and apositive seal will be formed there also. Once the guide is in its properposition within the casing, the end wall of the casing is crimped overthe guide to positively maintain the guide in its proper seatedposition.

An important feature of my invention consists in the fact that the thinwalled rubber section is put under very high compression as the guideand boot are forced into the casing. Still further, the action wherein aportion of the boot is squeezed tightly between the guide in the casingis important, in that it tends to make the rubber fill all crevices toprovide a perfect seal. Also, the uses of a thin rubber section for theseal minimizes the undesirable consequences resulting from the fact thatthe metal and rubber parts have a different coefficient of expansion.

It should also be understood that the flange 32 need not be formed atright angles to the axis of the boot but can be in the form of a cone.Also, an inwardly extending bead can be formed on the inner surface ofthe casing at a point adjacent the recess 28 of the inserted guide toaid in compressing the seal at this point after assembly.

In FIGURE 3, I have illustrated a slight modification of my device inwhich a diametrically enlarged head 17a is formed on the guide 17 and isadapted to seat upon a shoulder a formed at the upper end of the casing10. In this embodiment of my invention, the guide would simply be forcedinto the casing until the head 17a is seated upon the shoulder 10a, andthe outermost end of the casing would then be crimped over the outer endface 19 of the guide. In FIGURE 3, I have shown the device just priorto' the crimping or rolling operation.

The boot 24 is formed with an annular upstanding ring 35 formedintegrally therewith which is adapted to extend up within the annularwell 33. It is important to note however that the cross-sectional outerdiameter of the upstanding ring 35 is somewhat greater than thecross-sectional inner diameter of the well 33 so that when the piston 16is fitted through the guide 17 and into the boot 24 it will act to put acompression load on the ring 35. This embodiment of my invention isparticularly adapted to withstand considerable temperature variances.Since the lip 25 and ring 35 are maintained in compression expansion ofthe rubber as a result of increases in ambient temperature would onlyact to increase the effectiveness of the seal. On the other hand, when athermal sensitive power unit is subjected to very cold conditions theseal normally tends to pull away from the outer walls and tightenagainst the piston 16. In this embodiment of my invention the tendencyfor contraction will only act to increase the effectiveness of the sealbetween points. A

and B. Contraction of the rubber between points A and B will act tocause the boot to fit more tightly on the boss 21 and thereby increasethe effectiveness of the seal at that point. The lip 25 and ring 35 willbe under compression and the contraction of the rubber at those pointswould only tend to decrease the compression force somewhat. The ring 35and lip 25 however are relatively thin walled and the rubber contractionat these points would only be negligible and not impair theeffectiveness of the seal in any substantial degree.

I have also recognized the fact that there may be some water seepagealong the wall. of the piston 16 adjacent the guide 17 and that some ofthis water may become trapped between the end face 34 of the guide andthe upper end of the boot 24. Such water trapping can be substantiallyobviated by preventing the boot 24 from pulling away from the end face34 of the boss 21. The structure illustrated in FIGURE 6 achieves thisend. A thin walled collar 36 having an end face 37 depends from the endface 34 of the boss 21 and defines an extension of the bore 23. Thecollar 36 has a side wall 38 which diverges outwardly toward the endface 37 thereof and the upper end of the boot 24 is fitted around thiscollar. It will be observed that in this device the effective sealbetween the collar 36 and an adjacent portion of the boot 24 will becomegreater as the downward movement of the piston 16 tends to pull the boot24 downwardly within the casing 10. Of course, it is sufficient if thediverging wall of the collar 36 constitutes any annular section of thecollar and it is not essential that the wall diverge all the way fromthe end face 34 to the end face 37.

In the embodiment of FIGURE 7, a guide 40 is seated upon the shoulder10a formed at the upper end of the casing. The guide 40 is substantiallythe equivalent of the guide 17 heretofore described but for the factthat it has an elongated hollow boss 41 extending upwardly therefrom. Adepending boss 42 is formed intgerally therewith and has a side wall 43which is spaced from the straight side wall of the casing 10. An annularsegment of the wall 43 is tapered as at 44 to diverge outwardly from theend face 45 toward the end face 46 to form a recess. A diaphragm 47extends across the interior of the casing 10 and has an upturned lip 48with a head 49 formed on the upper end thereof which bead is receivedwithin the recess. A resilient plug 50 having an enlarged diameter baseportion and a reduced diameter top portion is fitted within acomplimentarily shaped section of the bore 51 and seats upon thediaphragm 47. An anti-chafe disk 52 seats, in turn, upon the plug 50 andserves as seat for the power member 53. The configuration of the lowerend of the bore 51 and the plug 50 serve to amplify the motion of thediaphragm 47 caused by expansion of the material within the casing 10 sothat an increase in piston stroke can be achieved in a manner well knownin the art.

In the embodiment of FIGURE 8 I have shown a temperature responsiveforce transmitting device which is much like that shown in FIGURE 4 butfor the fact that. a guide 55 is provide in place of the guide 17 whichis formed of a water permeable material. In the illustration the guideis formed of a sintered metal but many different types of waterpermeable materials would likewise be suitable. The advantage of havingthe guide formed of a water permeable material is that water trapping atthe inner face between the guide and the boot is obviated.

Attention is directed to the fact that in the thermal power unit of thisinvention, a recess has been formed in the depending boss and that thisfeature in combination with the fact that the boot or its equivalentserves to provide a positive fluid tight seal which will not readily berendered less effective by continued reciprocal movement of the piston.Also the method of forming a vertical seal has made possible the greatlyminiaturizing of thermal power elements without reducing the effectiveforce control of those elements.

It will be understood that various modifications and combinations of thefeatures of my invention may be accomplished by those versed in the artwithout departing from the spirit or scope of my contribution to theart, and I desire to claim all such modifications and combinations asproperly come within the scope of my invention.

I claim as my invention:

1. A temperature responsive force transmitting device comprising:

a casing having a side and an end wall and containing an expansionmaterial;

a guide member forcibly fitted Within one end of said casing and beingheld axially stationary therein by the force fit between the guide andthe casing, said guide having a depending portion spaced from the sidewall of said casing,

a seal extending across the interior of said casing having a lipinterposed between said depending portion of said guide and the saidside wall of said casing and being held in position substantially onlyby the force exerted on said lip by said depending portion of the guideand the side wall of the casing;

a power member guided. for movement within said guide and bottoming onsaid seal;

wherein said lip is firmly maintained between said side wall of saidcasing and said depending portion of said guide and wherein a portionthereof completely fills said recess.

2. A temperature responsive force transmitting device in accordance withclaim 1 wherein said casing has an opened end opposite said end wall andwherein a shoulder is formed about the inner side wall of said casingadjacent said open end thereof and facing outwardly of the interior ofthe casing and wherein said guide is seated upon said shoulder.

3. A temperature responsive force transmitting device in accordance withclaim 1 wherein said casing and said guide are cylindrically formed andwherein seal and lip comprise a resilient boot which completely fillsthe space between said depending portion of said guide and said sidewall of said casing.

4. A temperature responsive force transmitting device in accordance withclaim 1 wherein a portion of said casing is fitted over at least part ofthe exposed end of said guide to maintain said guide within said casing.

5. A temperature responsive force transmitting device in accordance withclaim 1 wherein said guide has a tapered side wall and wherein said lipof said seal is interposed between said tapered side wall and the sidewall of the casing.

6. A temperature responsive force transmitting device comprising:

a casing containing a thermal expansion material;

a guide fitted within and closing an end of asid casing and having aboss depending therefrom;

said boss having a side wall and an end face;

a seal extending across the interior of said casing having a lipinterposed between said depending boss and the said side wall of saidcasing;

a recess formed about said side wall of said boss;

2. guide bore formed within said guide and extending through the endface of said boss;

a recess formed within said end face around said bore; and

a power member guided for movement within said bore and bottoming onsaid seal;

wherein said lip is maintained in compression between said boss and saidside wall of said casing and wherein portions of said seal fill each ofsaid recesses.

7. A temperature responsive force transmitting device constructed inaccordance with claim 6 in which said guide and the said boss are formedof a water permeable material.

8. A temperature responsive force transmitting device comprising:

a casing having a side and an end wall and containing an expansionmaterial;

a guide fitted within and closing one end of said casing and having adepending boss spaced from the side Wall of said casing;

a seal extending across the interior of said casing having a lipinterposed between said depending boss and the said side wall of saidcasing;

a power member guided for movement within said guide and bottoming onsaid seal;

said depending boss having a side wall and an end face;

wherein at least a segment of the said side wall of said boss divergesoutwardly toward the said end face thereof;

and wherein said lip is maintained in compression between said side wallof said boss and said side wall of said casing.

9. A temperature responsive force transmitting device constructed inaccordance with claim 8 in which said guide and the said boss are formedof a water permeable material.

10. A temperature responsive force transmit-ting device comprising:

a casing having a side and an end wall and containing an expansionmaterial,

a guide fitted within and closing one end of said casing and having adepending portion spaced from the side wall of said casing,

said guide being formed of a water permeable material,

a seal extending across the interior of said casing having a lipinterposed between said depending portion of said guide and said sidewall of said casing,

a power member guided for movement within said guide and bottoming onsaid seal, and

a recess formed around the eripheral side wall of said dependingportion,

wherein said lip is firmly maintained between said side wall of saidcasing and said depending portion of said guide, and wherein a portionthereof completely fills said recess.

11. A temperature responsive force transmitting device comprising:

a casing having a side and an end wall and containing an expansionmaterial,

a guide fitted within and closing one end of said casing and having adepending portion spaced from the side Wall of said casing,

said guide being formed of a water permeable material,

said guide having a tapered side wall,

a seal extending across the interior of said casing having a lipinterposed between said tapered side wall of said guide and the sidewall of said casing,

a power member guided for movement within said guide and bottoming onsaid seal, and

a recess formed around the peripheral side wall of said dependingportion,

wherein said lip is firmly maintained between said side wall of saidcasing and said depending portion of said guide, and wherein a portionthereof completely fills said recess.

12. A temperature responsive force transmitting device in accordancewith claim 1 wherein said casing has a generally smooth cylindrical sidewall and wherein said lip of the seal is held in position between thesmooth cylindrical side wall and the depending portion of the guide.

13. A temperature responsive force transmitting device constructed inaccordance with claim 12 wherein said depending portion of said guideconverges to a smaller diameter at the end of said guide most closelyadjacent the end of the casing containing the expansion material.

References Cited UNITED STATES PATENTS 7/1940 Verne-t 73-368.3 X 7/1962Wagner 73--368.3

1. A TEMPERATURE RESPONSIVE FORCE TRANSMITTING DEVICE COMPRISING: ACASING HAVING A SIDE AND AN END WALL AND CONTAINING AN EXPANSIONMATERIAL; A GUIDE MEMBER FORCIBLY FITTED WITHIN ONE END OF SAID CASINGAND BEING HELD AXIALLY STATIONARY THEREIN BY THE FORCE FIT BETWEEN THEGUIDE AND THE CASING, SAID GUIDE HAVING A DEPENDING PORTION SPACED FROMTHE SIDE WALL OF SAID CASING. A SEAL EXTENDING ACROSS THE INTERIOR OFSAID CASING HAVING A LIP INTERPOSED BETWEEN SAID DEPENDING PORTION OFSAID GUIDE AND THE SAID SIDE WALL OF SAID CASING AND BEING HELD INPOSITION SUBSTANTIALLY ONLY BY THE FORCE EXERTED ON SAID LIP BY SAIDDEPENDING PORTION OF THE GUIDE AND THE SIDE WALL OF THE CASING; A POWERMEMBER GUIDED FOR MOVEMENT WITHIN SAID GUIDE AND BOTTOMING ON SAID SEAL;